How do you derive rectangular core width and height from area and aspect ratio?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
For area A and aspect ratio AR = width/height, width is sqrt(A x AR) and height is sqrt(A / AR). Keep units through every step.
Technical Explanation
The formulas turn one area and one shape choice into two physical dimensions. Illustrative example: A = 1000000 um^2 and AR = 1.0 gives width = 1000 um and height = 1000 um. Round only after checking legal grids and rows.
Formula Or Decision Rule
Width [um] = sqrt(A [um^2] x AR); height [um] = sqrt(A [um^2] / AR).
What To Check
• Warning sign: Rounded dimensions change area or land off the manufacturing, site, or block grid. • Inspect: choose one affected region, macro, row, pin, path, or net and trace the physical cause. • Correct: Snap deliberately, recompute actual area and utilisation, and record the rounded values.
Command Checks & Actions
• report_design -floorplan: reports the floorplan state understood by the tool
Run only the commands needed for this question. Save the report with the floorplan version and analysis context.Healthy, Suspicious & Hard-stop Results
• Healthy: For area A and aspect ratio AR = width/height, width is sqrt(A x AR) and height is sqrt(A / AR). Keep units through every step. • Suspicious: Rounded dimensions change area or land off the manufacturing, site, or block grid. • Hard stop: required legality or physical feasibility is missing or unexplained. Snap deliberately, recompute actual area and utilisation, and record the rounded values.
Common Mistake
Do not hide the symptom with an arbitrary utilisation, halo, channel, blockage, pin move, or die-size change. Rounded dimensions change area or land off the manufacturing, site, or block grid.
What The Interviewer Is Testing
The interviewer is testing whether you can connect “How do you derive rectangular core width and height from area and aspect ratio?” to measurable physical evidence and an owned correction.
Practical Example
Symptom: Rounded dimensions change area or land off the manufacturing, site, or block grid. Corrective path: Snap deliberately, recompute actual area and utilisation, and record the rounded values.
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